// Copyright (C) 2004-2021 Artifex Software, Inc.
//
// This file is part of MuPDF.
//
// MuPDF is free software: you can redistribute it and/or modify it under the
// terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
// details.
//
// You should have received a copy of the GNU Affero General Public License
// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
//
// Alternative licensing terms are available from the licensor.
// For commercial licensing, see <https://www.artifex.com/> or contact
// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
// CA 94129, USA, for further information.

#include "mupdf/fitz.h"

#include <string.h>
#include <assert.h>

// Thoughts for further optimisations:
// All paths start with MoveTo. We could probably avoid most cases where
// we store that. The next thing after a close must be a move.
// Commands are MOVE, LINE, HORIZ, VERT, DEGEN, CURVE, CURVEV, CURVEY, QUAD, RECT.
// We'd need to drop 2 to get us down to 3 bits.
// Commands can be followed by CLOSE. Use 1 bit for close.
// PDF 'RECT' implies close according to the spec, but I suspect
// we can ignore this as filling closes implicitly.
// We use a single bit in the path header to tell us whether we have
// a trailing move. Trailing moves can always be stripped when path
// construction completes.

typedef enum
{
	FZ_MOVETO = 'M',
	FZ_LINETO = 'L',
	FZ_DEGENLINETO = 'D',
	FZ_CURVETO = 'C',
	FZ_CURVETOV = 'V',
	FZ_CURVETOY = 'Y',
	FZ_HORIZTO = 'H',
	FZ_VERTTO = 'I',
	FZ_QUADTO = 'Q',
	FZ_RECTTO = 'R',
	FZ_MOVETOCLOSE = 'm',
	FZ_LINETOCLOSE = 'l',
	FZ_DEGENLINETOCLOSE = 'd',
	FZ_CURVETOCLOSE = 'c',
	FZ_CURVETOVCLOSE = 'v',
	FZ_CURVETOYCLOSE = 'y',
	FZ_HORIZTOCLOSE = 'h',
	FZ_VERTTOCLOSE = 'i',
	FZ_QUADTOCLOSE = 'q',
} fz_path_item_kind;

struct fz_path
{
	int8_t refs;
	uint8_t packed;
	int cmd_len, cmd_cap;
	unsigned char *cmds;
	int coord_len, coord_cap;
	float *coords;
	fz_point current;
	fz_point begin;
};

typedef struct
{
	int8_t refs;
	uint8_t packed;
	uint8_t coord_len;
	uint8_t cmd_len;
} fz_packed_path;

/*
	Paths are created UNPACKED. That means we have a fz_path
	structure with coords and cmds pointing to malloced blocks.

	After they have been completely constructed, callers may choose
	to 'pack' them into some target block of memory. If if coord_len
	and cmd_len are both < 256, then they are PACKED_FLAT into an
	fz_packed_path with the coords and cmds in the bytes afterwards,
	all inside the target block. If they cannot be accomodated in
	that way, then they are PACKED_OPEN, where an fz_path is put
	into the target block, and cmds and coords remain pointers to
	allocated blocks.
*/
enum
{
	FZ_PATH_UNPACKED = 0,
	FZ_PATH_PACKED_FLAT = 1,
	FZ_PATH_PACKED_OPEN = 2
};

#define LAST_CMD(path) ((path)->cmd_len > 0 ? (path)->cmds[(path)->cmd_len-1] : 0)

fz_path *
fz_new_path(fz_context *ctx)
{
	fz_path *path;

	path = fz_malloc_struct(ctx, fz_path);
	path->refs = 1;
	path->packed = FZ_PATH_UNPACKED;
	path->current.x = 0;
	path->current.y = 0;
	path->begin.x = 0;
	path->begin.y = 0;

	return path;
}

/*
	Take an additional reference to
	a path.

	No modifications should be carried out on a path
	to which more than one reference is held, as
	this can cause race conditions.
*/
fz_path *
fz_keep_path(fz_context *ctx, const fz_path *pathc)
{
	fz_path *path = (fz_path *)pathc; /* Explicit cast away of const */
	int trimmable = 0;

	if (path == NULL)
		return NULL;
	fz_lock(ctx, FZ_LOCK_ALLOC);
	/* Technically, we should only access ->refs with the lock held,
	 * so do that here. We can't actually do the trimming here, because
	 * to do so would do memory accesses with the ALLOC lock held. */
	if (path->refs == 1 && path->packed == FZ_PATH_UNPACKED)
		trimmable = 1;
	fz_keep_imp8_locked(ctx, path, &path->refs);
	fz_unlock(ctx, FZ_LOCK_ALLOC);

	/* This is thread safe, because we know that the only person
	 * holding a reference to this thread is us. */
	if (trimmable)
		fz_trim_path(ctx, path);

	return path;
}

void
fz_drop_path(fz_context *ctx, const fz_path *pathc)
{
	fz_path *path = (fz_path *)pathc; /* Explicit cast away of const */

	if (fz_drop_imp8(ctx, path, &path->refs))
	{
		if (path->packed != FZ_PATH_PACKED_FLAT)
		{
			fz_free(ctx, path->cmds);
			fz_free(ctx, path->coords);
		}
		if (path->packed == FZ_PATH_UNPACKED)
			fz_free(ctx, path);
	}
}

int fz_packed_path_size(const fz_path *path)
{
	switch (path->packed)
	{
	case FZ_PATH_UNPACKED:
		if (path->cmd_len > 255 || path->coord_len > 255)
			return sizeof(fz_path);
		return sizeof(fz_packed_path) + sizeof(float) * path->coord_len + sizeof(uint8_t) * path->cmd_len;
	case FZ_PATH_PACKED_OPEN:
		return sizeof(fz_path);
	case FZ_PATH_PACKED_FLAT:
	{
		fz_packed_path *pack = (fz_packed_path *)path;
		return sizeof(fz_packed_path) + sizeof(float) * pack->coord_len + sizeof(uint8_t) * pack->cmd_len;
	}
	default:
		assert("This never happens" == NULL);
		return 0;
	}
}

size_t
fz_pack_path(fz_context *ctx, uint8_t *pack_, const fz_path *path)
{
	uint8_t *ptr;
	size_t size;

	if (path->packed == FZ_PATH_PACKED_FLAT)
	{
		fz_packed_path *pack = (fz_packed_path *)path;
		fz_packed_path *out = (fz_packed_path *)pack_;
		size = sizeof(fz_packed_path) + sizeof(float) * pack->coord_len + sizeof(uint8_t) * pack->cmd_len;

		if (out)
		{
			out->refs = 1;
			out->packed = FZ_PATH_PACKED_FLAT;
			out->coord_len = pack->coord_len;
			out->cmd_len = pack->cmd_len;
			memcpy(&out[1], &pack[1], size - sizeof(*out));
		}
		return size;
	}

	size = sizeof(fz_packed_path) + sizeof(float) * path->coord_len + sizeof(uint8_t) * path->cmd_len;

	/* If the path can't be packed flat, then pack it open */
	if (path->cmd_len > 255 || path->coord_len > 255)
	{
		fz_path *pack = (fz_path *)pack_;

		if (pack != NULL)
		{
			pack->refs = 1;
			pack->packed = FZ_PATH_PACKED_OPEN;
			pack->current.x = 0;
			pack->current.y = 0;
			pack->begin.x = 0;
			pack->begin.y = 0;
			pack->coord_cap = path->coord_len;
			pack->coord_len = path->coord_len;
			pack->cmd_cap = path->cmd_len;
			pack->cmd_len = path->cmd_len;
			pack->coords = Memento_label(fz_malloc_array(ctx, path->coord_len, float), "path_packed_coords");
			fz_try(ctx)
			{
				pack->cmds = Memento_label(fz_malloc_array(ctx, path->cmd_len, uint8_t), "path_packed_cmds");
			}
			fz_catch(ctx)
			{
				fz_free(ctx, pack->coords);
				fz_rethrow(ctx);
			}
			memcpy(pack->coords, path->coords, sizeof(float) * path->coord_len);
			memcpy(pack->cmds, path->cmds, sizeof(uint8_t) * path->cmd_len);
		}
		return sizeof(fz_path);
	}
	else
	{
		fz_packed_path *pack = (fz_packed_path *)pack_;

		if (pack != NULL)
		{
			pack->refs = 1;
			pack->packed = FZ_PATH_PACKED_FLAT;
			pack->cmd_len = path->cmd_len;
			pack->coord_len = path->coord_len;
			ptr = (uint8_t *)&pack[1];
			memcpy(ptr, path->coords, sizeof(float) * path->coord_len);
			ptr += sizeof(float) * path->coord_len;
			memcpy(ptr, path->cmds, sizeof(uint8_t) * path->cmd_len);
		}

		return size;
	}
}

static void
push_cmd(fz_context *ctx, fz_path *path, int cmd)
{
	if (path->refs != 1)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "cannot modify shared paths");

	if (path->cmd_len + 1 >= path->cmd_cap)
	{
		int new_cmd_cap = fz_maxi(16, path->cmd_cap * 2);
		path->cmds = fz_realloc_array(ctx, path->cmds, new_cmd_cap, unsigned char);
		path->cmd_cap = new_cmd_cap;
	}

	path->cmds[path->cmd_len++] = cmd;
}

static void
push_coord(fz_context *ctx, fz_path *path, float x, float y)
{
	if (path->coord_len + 2 >= path->coord_cap)
	{
		int new_coord_cap = fz_maxi(32, path->coord_cap * 2);
		path->coords = fz_realloc_array(ctx, path->coords, new_coord_cap, float);
		path->coord_cap = new_coord_cap;
	}

	path->coords[path->coord_len++] = x;
	path->coords[path->coord_len++] = y;

	path->current.x = x;
	path->current.y = y;
}

static void
push_ord(fz_context *ctx, fz_path *path, float xy, int isx)
{
	if (path->coord_len + 1 >= path->coord_cap)
	{
		int new_coord_cap = fz_maxi(32, path->coord_cap * 2);
		path->coords = fz_realloc_array(ctx, path->coords, new_coord_cap, float);
		path->coord_cap = new_coord_cap;
	}

	path->coords[path->coord_len++] = xy;

	if (isx)
		path->current.x = xy;
	else
		path->current.y = xy;
}

fz_point
fz_currentpoint(fz_context *ctx, fz_path *path)
{
	return path->current;
}

void
fz_moveto(fz_context *ctx, fz_path *path, float x, float y)
{
	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Cannot modify a packed path");

	if (path->cmd_len > 0 && LAST_CMD(path) == FZ_MOVETO)
	{
		/* Collapse moveto followed by moveto. */
		path->coords[path->coord_len-2] = x;
		path->coords[path->coord_len-1] = y;
		path->current.x = x;
		path->current.y = y;
		path->begin = path->current;
		return;
	}

	push_cmd(ctx, path, FZ_MOVETO);
	push_coord(ctx, path, x, y);

	path->begin = path->current;
}

void
fz_lineto(fz_context *ctx, fz_path *path, float x, float y)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "lineto with no current point");
		return;
	}

	/* (Anything other than MoveTo) followed by (LineTo the same place) is a nop */
	if (LAST_CMD(path) != FZ_MOVETO && x0 == x && y0 == y)
		return;

	if (x0 == x)
	{
		if (y0 == y)
		{
			if (LAST_CMD(path) != FZ_MOVETO)
				return;
			push_cmd(ctx, path, FZ_DEGENLINETO);
		}
		else
		{
			push_cmd(ctx, path, FZ_VERTTO);
			push_ord(ctx, path, y, 0);
		}
	}
	else if (y0 == y)
	{
		push_cmd(ctx, path, FZ_HORIZTO);
		push_ord(ctx, path, x, 1);
	}
	else
	{
		push_cmd(ctx, path, FZ_LINETO);
		push_coord(ctx, path, x, y);
	}
}

void
fz_curveto(fz_context *ctx, fz_path *path,
	float x1, float y1,
	float x2, float y2,
	float x3, float y3)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "curveto with no current point");
		return;
	}

	/* Check for degenerate cases: */
	if (x0 == x1 && y0 == y1)
	{
		if (x2 == x3 && y2 == y3)
		{
			/* If (x1,y1)==(x2,y2) and prev wasn't a moveto, then skip */
			if (x1 == x2 && y1 == y2 && LAST_CMD(path) != FZ_MOVETO)
				return;
			/* Otherwise a line will suffice */
			fz_lineto(ctx, path, x3, y3);
		}
		else if (x1 == x2 && y1 == y2)
		{
			/* A line will suffice */
			fz_lineto(ctx, path, x3, y3);
		}
		else
			fz_curvetov(ctx, path, x2, y2, x3, y3);
		return;
	}
	else if (x2 == x3 && y2 == y3)
	{
		if (x1 == x2 && y1 == y2)
		{
			/* A line will suffice */
			fz_lineto(ctx, path, x3, y3);
		}
		else
			fz_curvetoy(ctx, path, x1, y1, x3, y3);
		return;
	}

	push_cmd(ctx, path, FZ_CURVETO);
	push_coord(ctx, path, x1, y1);
	push_coord(ctx, path, x2, y2);
	push_coord(ctx, path, x3, y3);
}

void
fz_quadto(fz_context *ctx, fz_path *path,
	float x1, float y1,
	float x2, float y2)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "quadto with no current point");
		return;
	}

	/* Check for degenerate cases: */
	if ((x0 == x1 && y0 == y1) || (x1 == x2 && y1 == y2))
	{
		if (x0 == x2 && y0 == y2 && LAST_CMD(path) != FZ_MOVETO)
			return;
		/* A line will suffice */
		fz_lineto(ctx, path, x2, y2);
		return;
	}

	push_cmd(ctx, path, FZ_QUADTO);
	push_coord(ctx, path, x1, y1);
	push_coord(ctx, path, x2, y2);
}

void
fz_curvetov(fz_context *ctx, fz_path *path, float x2, float y2, float x3, float y3)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "curveto with no current point");
		return;
	}

	/* Check for degenerate cases: */
	if (x2 == x3 && y2 == y3)
	{
		/* If (x0,y0)==(x2,y2) and prev wasn't a moveto, then skip */
		if (x0 == x2 && y0 == y2 && LAST_CMD(path) != FZ_MOVETO)
			return;
		/* Otherwise a line will suffice */
		fz_lineto(ctx, path, x3, y3);
	}
	else if (x0 == x2 && y0 == y2)
	{
		/* A line will suffice */
		fz_lineto(ctx, path, x3, y3);
	}

	push_cmd(ctx, path, FZ_CURVETOV);
	push_coord(ctx, path, x2, y2);
	push_coord(ctx, path, x3, y3);
}

void
fz_curvetoy(fz_context *ctx, fz_path *path, float x1, float y1, float x3, float y3)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "curveto with no current point");
		return;
	}

	/* Check for degenerate cases: */
	if (x1 == x3 && y1 == y3)
	{
		/* If (x0,y0)==(x1,y1) and prev wasn't a moveto, then skip */
		if (x0 == x1 && y0 == y1 && LAST_CMD(path) != FZ_MOVETO)
			return;
		/* Otherwise a line will suffice */
		fz_lineto(ctx, path, x3, y3);
	}

	push_cmd(ctx, path, FZ_CURVETOY);
	push_coord(ctx, path, x1, y1);
	push_coord(ctx, path, x3, y3);
}

void
fz_closepath(fz_context *ctx, fz_path *path)
{
	uint8_t rep;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Cannot modify a packed path");

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "closepath with no current point");
		return;
	}

	switch(LAST_CMD(path))
	{
	case FZ_MOVETO:
		rep = FZ_MOVETOCLOSE;
		break;
	case FZ_LINETO:
		rep = FZ_LINETOCLOSE;
		break;
	case FZ_DEGENLINETO:
		rep = FZ_DEGENLINETOCLOSE;
		break;
	case FZ_CURVETO:
		rep = FZ_CURVETOCLOSE;
		break;
	case FZ_CURVETOV:
		rep = FZ_CURVETOVCLOSE;
		break;
	case FZ_CURVETOY:
		rep = FZ_CURVETOYCLOSE;
		break;
	case FZ_HORIZTO:
		rep = FZ_HORIZTOCLOSE;
		break;
	case FZ_VERTTO:
		rep = FZ_VERTTOCLOSE;
		break;
	case FZ_QUADTO:
		rep = FZ_QUADTOCLOSE;
		break;
	case FZ_RECTTO:
		/* RectTo implies close */
		return;
	case FZ_MOVETOCLOSE:
	case FZ_LINETOCLOSE:
	case FZ_DEGENLINETOCLOSE:
	case FZ_CURVETOCLOSE:
	case FZ_CURVETOVCLOSE:
	case FZ_CURVETOYCLOSE:
	case FZ_HORIZTOCLOSE:
	case FZ_VERTTOCLOSE:
	case FZ_QUADTOCLOSE:
		/* CLOSE following a CLOSE is a NOP */
		return;
	default: /* default never happens */
	case 0:
		/* Closing an empty path is a NOP */
		return;
	}

	path->cmds[path->cmd_len-1] = rep;

	path->current = path->begin;
}

void
fz_rectto(fz_context *ctx, fz_path *path, float x1, float y1, float x2, float y2)
{
	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Cannot modify a packed path");

	if (path->cmd_len > 0 && LAST_CMD(path) == FZ_MOVETO)
	{
		/* Collapse moveto followed by rectto. */
		path->coord_len -= 2;
		path->cmd_len--;
	}

	push_cmd(ctx, path, FZ_RECTTO);
	push_coord(ctx, path, x1, y1);
	push_coord(ctx, path, x2, y2);

	path->current = path->begin;
}

static inline void bound_expand(fz_rect *r, fz_point p)
{
	if (p.x < r->x0) r->x0 = p.x;
	if (p.y < r->y0) r->y0 = p.y;
	if (p.x > r->x1) r->x1 = p.x;
	if (p.y > r->y1) r->y1 = p.y;
}

void fz_walk_path(fz_context *ctx, const fz_path *path, const fz_path_walker *proc, void *arg)
{
	int i, k, cmd_len;
	float x=0, y=0, sx=0, sy=0;
	uint8_t *cmds;
	float *coords;

	switch (path->packed)
	{
	case FZ_PATH_UNPACKED:
	case FZ_PATH_PACKED_OPEN:
		cmd_len = path->cmd_len;
		coords = path->coords;
		cmds = path->cmds;
		break;
	case FZ_PATH_PACKED_FLAT:
		cmd_len = ((fz_packed_path *)path)->cmd_len;
		coords = (float *)&((fz_packed_path *)path)[1];
		cmds = (uint8_t *)&coords[((fz_packed_path *)path)->coord_len];
		break;
	default:
		assert("This never happens" == NULL);
		return;
	}

	if (cmd_len == 0)
		return;

	for (k=0, i = 0; i < cmd_len; i++)
	{
		uint8_t cmd = cmds[i];

		switch (cmd)
		{
		case FZ_CURVETO:
		case FZ_CURVETOCLOSE:
			proc->curveto(ctx, arg,
					coords[k],
					coords[k+1],
					coords[k+2],
					coords[k+3],
					x = coords[k+4],
					y = coords[k+5]);
			k += 6;
			if (cmd == FZ_CURVETOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_CURVETOV:
		case FZ_CURVETOVCLOSE:
			if (proc->curvetov)
				proc->curvetov(ctx, arg,
						coords[k],
						coords[k+1],
						x = coords[k+2],
						y = coords[k+3]);
			else
			{
				proc->curveto(ctx, arg,
						x,
						y,
						coords[k],
						coords[k+1],
						coords[k+2],
						coords[k+3]);
				x = coords[k+2];
				y = coords[k+3];
			}
			k += 4;
			if (cmd == FZ_CURVETOVCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_CURVETOY:
		case FZ_CURVETOYCLOSE:
			if (proc->curvetoy)
				proc->curvetoy(ctx, arg,
						coords[k],
						coords[k+1],
						x = coords[k+2],
						y = coords[k+3]);
			else
				proc->curveto(ctx, arg,
						coords[k],
						coords[k+1],
						coords[k+2],
						coords[k+3],
						x = coords[k+2],
						y = coords[k+3]);
			k += 4;
			if (cmd == FZ_CURVETOYCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_QUADTO:
		case FZ_QUADTOCLOSE:
			if (proc->quadto)
				proc->quadto(ctx, arg,
					coords[k],
					coords[k+1],
					x = coords[k+2],
					y = coords[k+3]);
			else
			{
				float c2x = coords[k] * 2;
				float c2y = coords[k+1] * 2;
				float c1x = (x + c2x) / 3;
				float c1y = (y + c2y) / 3;
				x = coords[k+2];
				y = coords[k+3];
				c2x = (c2x + x) / 3;
				c2y = (c2y + y) / 3;

				proc->curveto(ctx, arg,
					c1x,
					c1y,
					c2x,
					c2y,
					x,
					y);
			}
			k += 4;
			if (cmd == FZ_QUADTOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_MOVETO:
		case FZ_MOVETOCLOSE:
			proc->moveto(ctx, arg,
				x = coords[k],
				y = coords[k+1]);
			k += 2;
			sx = x;
			sy = y;
			if (cmd == FZ_MOVETOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_LINETO:
		case FZ_LINETOCLOSE:
			proc->lineto(ctx, arg,
				x = coords[k],
				y = coords[k+1]);
			k += 2;
			if (cmd == FZ_LINETOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_HORIZTO:
		case FZ_HORIZTOCLOSE:
			proc->lineto(ctx, arg,
				x = coords[k],
				y);
			k += 1;
			if (cmd == FZ_HORIZTOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_VERTTO:
		case FZ_VERTTOCLOSE:
			proc->lineto(ctx, arg,
				x,
				y = coords[k]);
			k += 1;
			if (cmd == FZ_VERTTOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_DEGENLINETO:
		case FZ_DEGENLINETOCLOSE:
			proc->lineto(ctx, arg,
				x,
				y);
			if (cmd == FZ_DEGENLINETOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_RECTTO:
			if (proc->rectto)
			{
				proc->rectto(ctx, arg,
						x = coords[k],
						y = coords[k+1],
						coords[k+2],
						coords[k+3]);
			}
			else
			{
				proc->moveto(ctx, arg,
					x = coords[k],
					y = coords[k+1]);
				proc->lineto(ctx, arg,
					coords[k+2],
					coords[k+1]);
				proc->lineto(ctx, arg,
					coords[k+2],
					coords[k+3]);
				proc->lineto(ctx, arg,
					coords[k],
					coords[k+3]);
				if (proc->closepath)
					proc->closepath(ctx, arg);
			}
			sx = x;
			sy = y;
			k += 4;
			break;
		}
	}
}

typedef struct
{
	fz_matrix ctm;
	fz_rect rect;
	fz_point move;
	int trailing_move;
	int first;
} bound_path_arg;

static void
bound_moveto(fz_context *ctx, void *arg_, float x, float y)
{
	bound_path_arg *arg = (bound_path_arg *)arg_;
	arg->move = fz_transform_point_xy(x, y, arg->ctm);
	arg->trailing_move = 1;
}

static void
bound_lineto(fz_context *ctx, void *arg_, float x, float y)
{
	bound_path_arg *arg = (bound_path_arg *)arg_;
	fz_point p = fz_transform_point_xy(x, y, arg->ctm);
	if (arg->first)
	{
		arg->rect.x0 = arg->rect.x1 = p.x;
		arg->rect.y0 = arg->rect.y1 = p.y;
		arg->first = 0;
	}
	else
		bound_expand(&arg->rect, p);
	if (arg->trailing_move)
	{
		arg->trailing_move = 0;
		bound_expand(&arg->rect, arg->move);
	}
}

static void
bound_curveto(fz_context *ctx, void *arg_, float x1, float y1, float x2, float y2, float x3, float y3)
{
	bound_path_arg *arg = (bound_path_arg *)arg_;
	fz_point p = fz_transform_point_xy(x1, y1, arg->ctm);
	if (arg->first)
	{
		arg->rect.x0 = arg->rect.x1 = p.x;
		arg->rect.y0 = arg->rect.y1 = p.y;
		arg->first = 0;
	}
	else
		bound_expand(&arg->rect, p);
	bound_expand(&arg->rect, fz_transform_point_xy(x2, y2, arg->ctm));
	bound_expand(&arg->rect, fz_transform_point_xy(x3, y3, arg->ctm));
	if (arg->trailing_move)
	{
		arg->trailing_move = 0;
		bound_expand(&arg->rect, arg->move);
	}
}

static const fz_path_walker bound_path_walker =
{
	bound_moveto,
	bound_lineto,
	bound_curveto,
	NULL
};

fz_rect
fz_bound_path(fz_context *ctx, const fz_path *path, const fz_stroke_state *stroke, fz_matrix ctm)
{
	bound_path_arg arg;

	arg.ctm = ctm;
	arg.rect = fz_empty_rect;
	arg.trailing_move = 0;
	arg.first = 1;

	fz_walk_path(ctx, path, &bound_path_walker, &arg);

	if (!arg.first && stroke)
	{
		arg.rect = fz_adjust_rect_for_stroke(ctx, arg.rect, stroke, ctm);
	}

	return arg.rect;
}

fz_rect
fz_adjust_rect_for_stroke(fz_context *ctx, fz_rect r, const fz_stroke_state *stroke, fz_matrix ctm)
{
	float expand;

	if (!stroke)
		return r;

	expand = stroke->linewidth/2;
	if (expand == 0)
		expand = 0.5f;
	if (r.x1 == r.x0 || r.y1 == r.y0)
	{
		/* Mitring can't apply in this case. */
	}
	else if (stroke->linejoin == FZ_LINEJOIN_MITER && stroke->miterlimit > 0.5f)
	{
		/* miter limit is expressed in terms of the linewidth, not half the line width. */
		expand *= stroke->miterlimit * 2;
	}
	else if (stroke->linejoin == FZ_LINEJOIN_MITER_XPS && stroke->miterlimit > 1.0f)
	{
		/* for xps, miter limit is expressed in terms of half the linewidth. */
		expand *= stroke->miterlimit;
	}

	expand *= fz_matrix_max_expansion(ctm);

	r.x0 -= expand;
	r.y0 -= expand;
	r.x1 += expand;
	r.y1 += expand;
	return r;
}

void
fz_transform_path(fz_context *ctx, fz_path *path, fz_matrix ctm)
{
	int i, k, n;
	fz_point p, p1, p2, p3, q, s;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Cannot transform a packed path");

	if (ctm.b == 0 && ctm.c == 0)
	{
		/* Simple, in place transform */
		i = 0;
		k = 0;
		while (i < path->cmd_len)
		{
			uint8_t cmd = path->cmds[i];

			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_LINETO:
			case FZ_MOVETOCLOSE:
			case FZ_LINETOCLOSE:
				n = 1;
				break;
			case FZ_DEGENLINETO:
			case FZ_DEGENLINETOCLOSE:
				n = 0;
				break;
			case FZ_CURVETO:
			case FZ_CURVETOCLOSE:
				n = 3;
				break;
			case FZ_RECTTO:
				s.x = path->coords[k];
				s.y = path->coords[k+1];
				n = 2;
				break;
			case FZ_CURVETOV:
			case FZ_CURVETOY:
			case FZ_QUADTO:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
				n = 2;
				break;
			case FZ_HORIZTO:
			case FZ_HORIZTOCLOSE:
				q.x = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				n = 0;
				break;
			case FZ_VERTTO:
			case FZ_VERTTOCLOSE:
				q.y = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.y;
				n = 0;
				break;
			default:
				assert("Unknown path cmd" == NULL);
			}
			while (n > 0)
			{
				q.x = path->coords[k];
				q.y = path->coords[k+1];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				path->coords[k++] = p.y;
				n--;
			}
			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_MOVETOCLOSE:
				s = q;
				break;
			case FZ_LINETOCLOSE:
			case FZ_DEGENLINETOCLOSE:
			case FZ_CURVETOCLOSE:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
			case FZ_HORIZTOCLOSE:
			case FZ_VERTTOCLOSE:
			case FZ_RECTTO:
				q = s;
				break;
			}
			i++;
		}
	}
	else if (ctm.a == 0 && ctm.d == 0)
	{
		/* In place transform with command rewriting */
		i = 0;
		k = 0;
		while (i < path->cmd_len)
		{
			uint8_t cmd = path->cmds[i];

			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_LINETO:
			case FZ_MOVETOCLOSE:
			case FZ_LINETOCLOSE:
				n = 1;
				break;
			case FZ_DEGENLINETO:
			case FZ_DEGENLINETOCLOSE:
				n = 0;
				break;
			case FZ_CURVETO:
			case FZ_CURVETOCLOSE:
				n = 3;
				break;
			case FZ_RECTTO:
				s.x = path->coords[k];
				s.y = path->coords[k+1];
				n = 2;
				break;
			case FZ_CURVETOV:
			case FZ_CURVETOY:
			case FZ_QUADTO:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
				n = 2;
				break;
			case FZ_HORIZTO:
				q.x = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.y;
				path->cmds[i] = FZ_VERTTO;
				n = 0;
				break;
			case FZ_HORIZTOCLOSE:
				q.x = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.y;
				path->cmds[i] = FZ_VERTTOCLOSE;
				n = 0;
				break;
			case FZ_VERTTO:
				q.y = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				path->cmds[i] = FZ_HORIZTO;
				n = 0;
				break;
			case FZ_VERTTOCLOSE:
				q.y = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				path->cmds[i] = FZ_HORIZTOCLOSE;
				n = 0;
				break;
			default:
				assert("Unknown path cmd" == NULL);
			}
			while (n > 0)
			{
				q.x = path->coords[k];
				q.y = path->coords[k+1];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				path->coords[k++] = p.y;
				n--;
			}
			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_MOVETOCLOSE:
				s = q;
				break;
			case FZ_LINETOCLOSE:
			case FZ_DEGENLINETOCLOSE:
			case FZ_CURVETOCLOSE:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
			case FZ_HORIZTOCLOSE:
			case FZ_VERTTOCLOSE:
			case FZ_RECTTO:
				q = s;
				break;
			}
			i++;
		}
	}
	else
	{
		int extra_coord = 0;
		int extra_cmd = 0;
		int coord_read, coord_write, cmd_read, cmd_write;

		/* General case. Have to allow for rects/horiz/verts
		 * becoming non-rects/horiz/verts. */
		for (i = 0; i < path->cmd_len; i++)
		{
			uint8_t cmd = path->cmds[i];
			switch (cmd)
			{
			case FZ_HORIZTO:
			case FZ_VERTTO:
			case FZ_HORIZTOCLOSE:
			case FZ_VERTTOCLOSE:
				extra_coord += 1;
				break;
			case FZ_RECTTO:
				extra_coord += 2;
				extra_cmd += 3;
				break;
			default:
				/* Do nothing */
				break;
			}
		}
		if (path->cmd_len + extra_cmd < path->cmd_cap)
		{
			path->cmds = fz_realloc_array(ctx, path->cmds, path->cmd_len + extra_cmd, unsigned char);
			path->cmd_cap = path->cmd_len + extra_cmd;
		}
		if (path->coord_len + extra_coord < path->coord_cap)
		{
			path->coords = fz_realloc_array(ctx, path->coords, path->coord_len + extra_coord, float);
			path->coord_cap = path->coord_len + extra_coord;
		}
		memmove(path->cmds + extra_cmd, path->cmds, path->cmd_len * sizeof(unsigned char));
		path->cmd_len += extra_cmd;
		memmove(path->coords + extra_coord, path->coords, path->coord_len * sizeof(float));
		path->coord_len += extra_coord;

		for (cmd_write = 0, cmd_read = extra_cmd, coord_write = 0, coord_read = extra_coord; cmd_read < path->cmd_len; i += 2)
		{
			uint8_t cmd = path->cmds[cmd_write++] = path->cmds[cmd_read++];

			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_LINETO:
			case FZ_MOVETOCLOSE:
			case FZ_LINETOCLOSE:
				n = 1;
				break;
			case FZ_DEGENLINETO:
			case FZ_DEGENLINETOCLOSE:
				n = 0;
				break;
			case FZ_CURVETO:
			case FZ_CURVETOCLOSE:
				n = 3;
				break;
			case FZ_CURVETOV:
			case FZ_CURVETOY:
			case FZ_QUADTO:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
				n = 2;
				break;
			case FZ_RECTTO:
				p.x = path->coords[coord_read++];
				p.y = path->coords[coord_read++];
				p2.x = path->coords[coord_read++];
				p2.y = path->coords[coord_read++];
				p1.x = p2.x;
				p1.y = p.y;
				p3.x = p.x;
				p3.y = p2.y;
				s = p;
				p = fz_transform_point(p, ctm);
				p1 = fz_transform_point(p1, ctm);
				p2 = fz_transform_point(p2, ctm);
				p3 = fz_transform_point(p3, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->coords[coord_write++] = p1.x;
				path->coords[coord_write++] = p1.y;
				path->coords[coord_write++] = p2.x;
				path->coords[coord_write++] = p2.y;
				path->coords[coord_write++] = p3.x;
				path->coords[coord_write++] = p3.y;
				path->cmds[cmd_write-1] = FZ_MOVETO;
				path->cmds[cmd_write++] = FZ_LINETO;
				path->cmds[cmd_write++] = FZ_LINETO;
				path->cmds[cmd_write++] = FZ_LINETOCLOSE;
				n = 0;
				break;
			case FZ_HORIZTO:
				q.x = path->coords[coord_read++];
				p = fz_transform_point(q, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->cmds[cmd_write-1] = FZ_LINETO;
				n = 0;
				break;
			case FZ_HORIZTOCLOSE:
				p.x = path->coords[coord_read++];
				p.y = q.y;
				p = fz_transform_point(p, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->cmds[cmd_write-1] = FZ_LINETOCLOSE;
				q = s;
				n = 0;
				break;
			case FZ_VERTTO:
				q.y = path->coords[coord_read++];
				p = fz_transform_point(q, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->cmds[cmd_write-1] = FZ_LINETO;
				n = 0;
				break;
			case FZ_VERTTOCLOSE:
				p.x = q.x;
				p.y = path->coords[coord_read++];
				p = fz_transform_point(p, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->cmds[cmd_write-1] = FZ_LINETOCLOSE;
				q = s;
				n = 0;
				break;
			default:
				assert("Unknown path cmd" == NULL);
			}
			while (n > 0)
			{
				q.x = path->coords[coord_read++];
				q.y = path->coords[coord_read++];
				p = fz_transform_point(q, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				n--;
			}
			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_MOVETOCLOSE:
				s = q;
				break;
			case FZ_LINETOCLOSE:
			case FZ_DEGENLINETOCLOSE:
			case FZ_CURVETOCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_CURVETOVCLOSE:
			case FZ_QUADTOCLOSE:
			case FZ_HORIZTOCLOSE:
			case FZ_VERTTOCLOSE:
			case FZ_RECTTO:
				q = s;
				break;
			}
		}
	}
}

void fz_trim_path(fz_context *ctx, fz_path *path)
{
	if (path->packed)
		fz_throw(ctx, FZ_ERROR_ARGUMENT, "Can't trim a packed path");
	if (path->cmd_cap > path->cmd_len)
	{
		path->cmds = fz_realloc_array(ctx, path->cmds, path->cmd_len, unsigned char);
		path->cmd_cap = path->cmd_len;
	}
	if (path->coord_cap > path->coord_len)
	{
		path->coords = fz_realloc_array(ctx, path->coords, path->coord_len, float);
		path->coord_cap = path->coord_len;
	}
}

const fz_stroke_state fz_default_stroke_state = {
	-2, /* -2 is the magic number we use when we have stroke states stored on the stack */
	FZ_LINECAP_BUTT, FZ_LINECAP_BUTT, FZ_LINECAP_BUTT,
	FZ_LINEJOIN_MITER,
	1, 10,
	0, 0, { 0 }
};

fz_stroke_state *
fz_keep_stroke_state(fz_context *ctx, const fz_stroke_state *strokec)
{
	fz_stroke_state *stroke = (fz_stroke_state *)strokec; /* Explicit cast away of const */

	if (!stroke)
		return NULL;

	/* -2 is the magic number we use when we have stroke states stored on the stack */
	if (stroke->refs == -2)
		return fz_clone_stroke_state(ctx, stroke);

	return fz_keep_imp(ctx, stroke, &stroke->refs);
}

void
fz_drop_stroke_state(fz_context *ctx, const fz_stroke_state *strokec)
{
	fz_stroke_state *stroke = (fz_stroke_state *)strokec; /* Explicit cast away of const */

	if (fz_drop_imp(ctx, stroke, &stroke->refs))
		fz_free(ctx, stroke);
}

fz_stroke_state *
fz_new_stroke_state_with_dash_len(fz_context *ctx, int len)
{
	fz_stroke_state *state;

	len -= nelem(state->dash_list);
	if (len < 0)
		len = 0;

	state = Memento_label(fz_malloc(ctx, sizeof(*state) + sizeof(state->dash_list[0]) * len), "fz_stroke_state");
	state->refs = 1;
	state->start_cap = FZ_LINECAP_BUTT;
	state->dash_cap = FZ_LINECAP_BUTT;
	state->end_cap = FZ_LINECAP_BUTT;
	state->linejoin = FZ_LINEJOIN_MITER;
	state->linewidth = 1;
	state->miterlimit = 10;
	state->dash_phase = 0;
	state->dash_len = 0;
	memset(state->dash_list, 0, sizeof(state->dash_list[0]) * (len + nelem(state->dash_list)));

	return state;
}

fz_stroke_state *
fz_new_stroke_state(fz_context *ctx)
{
	return fz_new_stroke_state_with_dash_len(ctx, 0);
}

fz_stroke_state *
fz_clone_stroke_state(fz_context *ctx, fz_stroke_state *stroke)
{
	fz_stroke_state *clone = fz_new_stroke_state_with_dash_len(ctx, stroke->dash_len);
	int extra = stroke->dash_len - nelem(stroke->dash_list);
	int size = sizeof(*stroke) + sizeof(stroke->dash_list[0]) * extra;
	memcpy(clone, stroke, size);
	clone->refs = 1;
	return clone;
}

fz_stroke_state *
fz_unshare_stroke_state_with_dash_len(fz_context *ctx, fz_stroke_state *shared, int len)
{
	int single, unsize, shsize, shlen;
	fz_stroke_state *unshared;

	fz_lock(ctx, FZ_LOCK_ALLOC);
	single = (shared->refs == 1);
	fz_unlock(ctx, FZ_LOCK_ALLOC);

	shlen = shared->dash_len - nelem(shared->dash_list);
	if (shlen < 0)
		shlen = 0;
	shsize = sizeof(*shared) + sizeof(shared->dash_list[0]) * shlen;
	len -= nelem(shared->dash_list);
	if (len < 0)
		len = 0;
	if (single && shlen >= len)
		return shared;

	unsize = sizeof(*unshared) + sizeof(unshared->dash_list[0]) * len;
	unshared = Memento_label(fz_malloc(ctx, unsize), "fz_stroke_state");
	memcpy(unshared, shared, (shsize > unsize ? unsize : shsize));
	unshared->refs = 1;

	if (fz_drop_imp(ctx, shared, &shared->refs))
		fz_free(ctx, shared);
	return unshared;
}

fz_stroke_state *
fz_unshare_stroke_state(fz_context *ctx, fz_stroke_state *shared)
{
	return fz_unshare_stroke_state_with_dash_len(ctx, shared, shared->dash_len);
}

static void *
clone_block(fz_context *ctx, void *block, size_t len)
{
	void *target;

	if (len == 0 || block == NULL)
		return NULL;

	target = fz_malloc(ctx, len);
	memcpy(target, block, len);
	return target;
}

fz_path *
fz_clone_path(fz_context *ctx, fz_path *path)
{
	fz_path *new_path;

	assert(ctx != NULL);

	if (path == NULL)
		return NULL;

	new_path = fz_malloc_struct(ctx, fz_path);
	new_path->refs = 1;
	new_path->packed = FZ_PATH_UNPACKED;
	fz_try(ctx)
	{
		switch(path->packed)
		{
		case FZ_PATH_UNPACKED:
		case FZ_PATH_PACKED_OPEN:
			new_path->cmd_len = path->cmd_len;
			new_path->cmd_cap = path->cmd_cap;
			new_path->cmds = Memento_label(clone_block(ctx, path->cmds, path->cmd_cap), "path_cmds");
			new_path->coord_len = path->coord_len;
			new_path->coord_cap = path->coord_cap;
			new_path->coords = Memento_label(clone_block(ctx, path->coords, sizeof(float)*path->coord_cap), "path_coords");
			new_path->current = path->current;
			new_path->begin = path->begin;
			break;
		case FZ_PATH_PACKED_FLAT:
			{
				uint8_t *data;
				float *xy;
				int i;
				fz_packed_path *ppath = (fz_packed_path *)path;

				new_path->cmd_len = ppath->cmd_len;
				new_path->cmd_cap = ppath->cmd_len;
				new_path->coord_len = ppath->coord_len;
				new_path->coord_cap = ppath->coord_len;
				data = (uint8_t *)&ppath[1];
				new_path->coords = Memento_label(clone_block(ctx, data, sizeof(float)*path->coord_cap), "path_coords");
				data += sizeof(float) * path->coord_cap;
				new_path->cmds = Memento_label(clone_block(ctx, data, path->cmd_cap), "path_cmds");
				xy = new_path->coords;
				for (i = 0; i < new_path->cmd_len; i++)
				{
					switch (new_path->cmds[i])
					{
					case FZ_MOVETOCLOSE:
					case FZ_MOVETO:
						new_path->current.x = *xy++;
						new_path->current.y = *xy++;
						new_path->begin.x = new_path->current.x;
						new_path->begin.y = new_path->current.y;
						break;
					case FZ_CURVETO:
						xy += 2;
						/* fallthrough */
					case FZ_CURVETOV:
					case FZ_CURVETOY:
					case FZ_QUADTO:
						/* fallthrough */
						xy += 2;
					case FZ_LINETO:
						new_path->current.x = *xy++;
						new_path->current.y = *xy++;
						break;
					case FZ_DEGENLINETO:
						break;
					case FZ_HORIZTO:
						new_path->current.x = *xy++;
						break;
					case FZ_VERTTO:
						new_path->current.y = *xy++;
						break;
					case FZ_RECTTO:
						xy += 2;
						break;
					case FZ_CURVETOCLOSE:
						xy += 2;
						/* fallthrough */
					case FZ_CURVETOVCLOSE:
					case FZ_CURVETOYCLOSE:
					case FZ_QUADTOCLOSE:
					case FZ_LINETOCLOSE:
						xy++;
						/* fallthrough */
					case FZ_HORIZTOCLOSE:
					case FZ_VERTTOCLOSE:
						xy++;
						/* fallthrough */
					case FZ_DEGENLINETOCLOSE:
						new_path->current.x = new_path->begin.x;
						new_path->current.y = new_path->begin.y;
						break;
					}
				}
			}
		default:
			assert(!"Unknown packing method found in path");
		}
	}
	fz_catch(ctx)
	{
		fz_free(ctx, new_path->coords);
		fz_free(ctx, new_path->cmds);
		fz_free(ctx, new_path);
		fz_rethrow(ctx);
	}
	return new_path;
}
